PROJECT SUMMARY Postpartum depression (PPD) is a prevalent disorder associated with impairments in maternal functioning, risk of suicide and comorbidity, and negative effects on offspring development. The peripartum period is marked by dramatic neurobiological changes, yet the impact of these changes on emotional reactivity remain poorly understood. Longitudinal research examining dynamic change across this period is critically needed to chart trajectories of change and determine when women at risk for PPD can be reliably identified in order to facilitate effective timing of prevention to mitigate risk. To this end, we have developed and tested the feasibility of a method for measuring neural, physiological, and behavioral responses to highly-salient emotional stimuli for pregnant women and new mothers (i.e., infant distress cues). We will assess 100 pregnant women at 20 weeks gestation (2nd trimester; time 1). We will oversample for depression risk, such that at least 50% of the sample will have a history of treatment for depression, elevated current depressive symptoms, and/or history of childhood adversity. A second session will be scheduled for 34 weeks gestation (3rd trimester; time 2), and a final session will be scheduled for 8 weeks postpartum (time 3). At each assessment, women will complete an infant face matching task in which they match distressed, happy, and neutral infant faces and shapes with and without interspersed infant crying sounds. Repeated assessments using this task will allow us to chart peripartum trajectories of emotional reactivity with the potential to improve prediction of PPD. Event-related potentials (ERPs), particularly the late positive potential (LPP), a reliable measure of motivated attention and arousal processes, will be used to measure emotional reactivity at the neural level. Heart rate variability (HRV) decreases from the no-cry to cry condition will measure physiological responses to infant distress. Finally, increases in reaction time (RT) when matching faces in the cry vs. no-cry condition will be a behavioral indicator of emotional reactivity. At time 1, diagnostic interviews will assess lifetime depression history, and new onsets of depressive episodes will be assessed at time 2 and 3. For sensitive detection of PPD symptoms, women will complete depressive symptom measures through an electronic questionnaire the week following childbirth and continuing biweekly for 8 weeks. This project will allow us to chart trajectories of neural, physiological, and behavioral reactivity to infant distress cues across pregnancy and into the postpartum period (Specific Aim 1). In addition, we will test competing predictors of PPD symptoms considering both time 1 neural, physiological, and behavioral reactivity to infant distress, as well as change in reactivity to infant distress from mid-pregnancy to postpartum (Specific Aim 2). This exploratory project will integrate an ecologically-valid emotion paradigm with longitudinal, multimodal assessment and be the first to chart trajectories of change in emotional reactivity across the peripartum period to improve prediction of PPD.